1. Field of the Invention
The present invention relates to a character processing apparatus such as typewriter or word processor.
2. Description of the Prior Art
In a key entry device of a prior art text processing apparatus such as typewriter or word processor, a repeat function is attained by depressing a double action key or continuously depressing a key for a predetermined time period. For example, in the word processor, a character "A" is sequentially entered by continuously depressing a key of the character "A" for the predetermined time period. More specifically, when the key for the character "A" is depressed, an output from a key entry device is processed by a conventional interruption function to prevent loss of the input character and stored in a memory (key buffer) used to temporarily store the keyed information and then it is read out from the key buffer to complete the key input operation. Because a key input speed is faster than a character processing speed, if the key for the character "A" is continuously depressed, many codes of the character "A" (for example, 41H in ASCII code) are stored in the key buffer.
Accordingly, even if an operator releases the key for the character "A", the codes of the character "A" stored in the buffer are sequentially output. This problem is remarkable e.g., when a cursor shift key is continuously depressed. When the operator wants to shift the cursor, the cursor shift key is continuously depressed. If the operator releases the cursor shift key when the cursor comes to a desired position, the cursor is usually shifted past the desired position because of the cursor shift key signals stored in the key buffer. In order to avoid the above problem, in prior art apparatus, the key input from the same character key is accepted at a longer time interval than a processing time required for a lowest character processing speed key (for example, cursor up key when a cursor is at the topmost position on a screen). (This is not applicable for key inputs from different character keys.)
However, this method has a significant disadvantage that the input speed for the same character is very low and a long time is required to move the cursor to a desired position. In addition, there is a risk that the same characters are input at a high speed. (for example, "mm" in "command" is dropped.)